I recently read a post on Dave MacLeod's blog that got me thinking. It seems to me there are a lot of MacLeod haters on MP, but I think I'll ask anyway. Anyway, in this post Dave implies that he normally runs BEFORE breakfast so as to "to get into fat oxidation quicker". I had never heard of this before, but a little googling seems to tell me this is a good way to burn more fat (this paper looks like it supports this idea). From the cited paper it looks like you also need to nail the intensity in order to get the maximum fat oxidation rate.

Does anyone else systematically do this to burn fat more effectively? Anyone have any specific experience on this topic? Any research that refutes this idea?

If you constantly eat a ton of carbs, then yes, it is better to run on an empty stomach. If you eat lower carbs than it doesn't matter as much. excessive carbohydrate consumtion causes an insulin release, and one of the primary functions of insulin is fat storage. Your body CANNOT burn fat in the presence of insulin.

I'd be interested to see studies on this as well. It certainly makes sense theoretically especially doing so in the morning when your body is already in oxidation mode rather than eating and burning through that free glucose.

Eric Carlos wrote:

Your body CANNOT burn fat in the presence of insulin.

While I agree with what you're getting at, fasting insulin levels are not normally zero, so it's really more of a gradient than an absolute. Our bodies typically use multiple energy systems simultaneously, simply shifting the rates at which each is utilized.

This study mentions research confirming your thoughts though interestingly they note that (on animals) a "fed state" of high fat did not inhibit oxidation, rather increasing it. Neat! Again, makes sense that throwing carbs down the hatch would be the biggest inhibitor (which I think is what Eric was saying).

The miltary, in boot camp we would always run and workout before breakfast, after 8 weeks almost everyone had lost a ton of excess body fat.

Isn't that kind of a given tho.

But I do agree with a hard work out before eating much. In fact I prefer to get out and do a hard ride, don't run anymore, before eating much.

I remember reading this guys, Lito Tejada Flores, book on XC skiing. There was something about caffeine aiding in burning fat. He recommended drinking a caffeinated drink before or during a race to add quick energy from fat.

As to the rest it's over my head or interest at this time.

Depending on the type of climbing of course, but I always felt a little fat in reserve was a good thing.

Does anyone else systematically do this to burn fat more effectively? Anyone have any specific experience on this topic? Any research that refutes this idea?

Mr. MacLeod is a climber not exercise physiologist. It is probably best to consult medical literature for the advice, and your posted link is a step in the right direction. Unfortunately you seem to lack reading comprehension to interpret research presented in the article correctly. It appears that you want to make the case for more effective fat oxidation fasting. The article you quoted does not investigate effects of fasting on oxidation, it examines effects of exercise intensity on fat oxidation. It presents results to demonstrate that fat oxidation rates positively correlate with the VO2max, and, of course, the exercise intensity. So, what to take out that article? I believe the following paragraph is what you are really interested in:

"" wrote:

The finding that at the same relative intensity trained individuals ( i.e. individuals with a higher VO2max ) have greater rates of fatty acid oxidation, can be explained by the fact that the trained individuals are exercising at a higher absolute work rate

I suspect that the fasting phase was introduce to make sure that folks had their blood sugar at a certain level, even then there is a discussion on the effects of variation in diet on the results

To recap - Fitter individuals will oxidize more fatty acids at ~65% Vo2max effort because they produce more power at that effort.

Now, how does one increase VO2max? - I would suggest running a simple search, but IIRC exercise after fasting at 65% max effort is not it.

If your running goals include changIng around body composition, relative intensity is important.

Lots of folks enjoy early, cool, running. Lots of folks sched is driven by time constraints, and burping up oatmeal or eggs On the am run is no fun. Experiment.

If you're gonna run more than 4 miles or so in a fasted state, some carbs to prime the pump likely will be important. One energy gel, dissolved in a water bottle is popular for the early am run. Recovery nutrition after a fasted state run is SUPER important.

There was something about caffeine aiding in burning fat. He recommended drinking a caffeinated drink before or during a race to add quick energy from fat. As to the rest it's over my head or interest at this time. Depending on the type of climbing of course, but I always felt a little fat in reserve was a good thing.

Caffeine is a thermogenic. It raises your internal body temperature. This is why it is popular in all diet pills. Your body cannot begin to burn fat until it reaches a certain internal temperature. By taking caffeine it helps your body reach that temperature quicker. It also being a stimulant helps energy and focus as well.

Take a look at CLA. It is a supplement that was developed to help the Canadian army train in cold temperatures, and then used by Austrailian distance swimmers to combat the effects of prolonged water emerson. Tests have shown that it will decrease body fat by 10% even in non active people due to its thermogenic properties.

Running on an empty stomach after a 8 hour fast is just foolish. It may help Dave loose a few pounds so he can send his latest project, but it is likely to lead to Metabolic Disorder if practiced for long periods. You are putting your body in a calorie deficient state, when you eat afterwards your body will have a huge insulin spike and convert most of the calories into fat. Plenty of studies have shown that fasting actually increases your bodies propensity to store fat.

Eat small balanced meals, keep your glucose (and insulin) levels at a consistent low level and you will have a much better chance of loosing body fat.

Take a look at CLA. It is a supplement that was developed to help the Canadian army train in cold temperatures, and then used by Austrailian distance swimmers to combat the effects of prolonged water emerson. Tests have shown that it will decrease body fat by 10% even in non active people due to its thermogenic properties. Running on an empty stomach after a 8 hour fast is just foolish. It may help Dave loose a few pounds so he can send his latest project, but it is likely to lead to Metabolic Disorder if practiced for long periods. You are putting your body in a calorie deficient state, when you eat afterwards your body will have a huge insulin spike and convert most of the calories into fat. Plenty of studies have shown that fasting actually increases your bodies propensity to store fat. Eat small balanced meals, keep your glucose (and insulin) levels at a consistent low level and you will have a much better chance of loosing body fat.

It really depends on WHAT you're eating...Also, if you've been running for awhile I think the insulin would direct some of those calories into the muscles cells to replenish glycogen.

This is true and does work IME. I subscribe to a form of the Paleo diet, where my diet and exercise regiment are intertwined. If you think about it from an evolutionary standpoint, humans had to chase down game before they could eat it. We had to walk through the forest to collect nuts and berries and what not.

This may be a simple approach that is devoid of scientific mumbo jumbo, but it has always worked for me. Eat a meal high in animal protein after intense cardio or resistance training. A small snack of almonds and strawberries and a glass of water are good for before the exercise if you need something.

The human body is designed to run on E so to speak for longer than one might expect. I've completed long hikes/climbs on a hand full of almonds, raspberries, and a few sips of water. Then had a fatty steak for dinner. But then, that's what works for me. Everyone's different.

I get bad side stitches unless I run on a totally empty stomach, so I always run first thing in the morning before eating. I don't run very far (4 miles is my standard distance), but I've never had problems from low energy and it has never seemed to be burning muscle.

Has it helped me burn more fat? I don't know. It's easy for me to keep my weight low, but whether that is because of the running or something else I can't say.

I think (as usual) the science is murky behind all this. One of the problems is that not all studies examine the same exercise intensity and duration, thus making them harder to compare.

I think it does seem to be the case that fat oxidation is higher when exercising during a fasted state (and what does 'fasted state' mean? In some studies it means overnight, in others it means 3 hours since last meal). But usually this occurs during intensities of 50-70% max heart rate...which doesn't really correlate to a very intense workout (especially if you are moderately fit or better).

Keep in mind that the less glucose you have available the less intensely you can exercise. But the more intensely you can exercise the more calories you can burn and the more efficiently you oxidize fat as well.

So what do you want to do? I think having adequate glucose and being able to exercise at high intensities is far more preferable and will make you fitter and better conditioned far more quickly.

Also, if you have any actual aerobically-based training GOALS, then this empty-stomach method will most likely hold you back.

Stickygreens wrote:

The miltary, in boot camp we would always run and workout before breakfast, after 8 weeks almost everyone had lost a ton of excess body fat.

This would happen in your scenario regardless of "when" you did it.

Kevin Stricker wrote:

Take a look at CLA. ... Tests have shown that it will decrease body fat by 10% even in non active people due to its thermogenic properties.

Actually I do not believe CLA has ever been substantiated to really be effective. Certainly the body fat loss claims have been over-hyped greatly.

Thanks, Kevin. I found a recent meta-analysis which analyzed 7 studies (which qualified out of 15 randomized controlled trials, although 4 of the 7 still had major methodology problems) and concluded CLA seemed to have a statistical significance in enhancing fat loss for a duration of 6 months or more, albeit it was a small amount of weight difference lost (2 lbs +/- 1?).

Their conclusion: "The magnitude of these effects is small, and the clinical relevance is uncertain. Adverse events included constipation, diarrhea, and soft stools. The evidence from randomized controlled trials does not convincingly show that CLA intake generates any clinically relevant effects on body composition on the long term."

I found it interesting that the study you linked, however, also stated their subjects were offered a fitness program in conjunction with this study (and the fitness program was rated either easy or more intense), but no further reference or control regarding any physical training was ever written up...which I do find to be problematic. (How can you attribute fat loss in an individual to derive only from ingesting CLA when they also may have just started a fitness program?)

Your link summarized: "In conclusion, we want to emphasize that the beneficial effects of CLA with regard to BFM (body fat mass) and LBM (lean body mass) are promising. The number of subjects in this study was relatively small and may thus be a limiting factor in reaching general conclusions. However, at present, a dose of 3.4 g CLA/d for 12 wk seems to be sufficient to reduce BFM significantly in overweight and obese humans. A conclusion regarding the optimal dose of CLA and duration of treatment cannot be made on the basis of these limited data, but the current data provide a solid platform for future studies."

Actually the study I posted did in fact go into the levels of training for all of the groups(table 4). The most interesting thing is that those who received the higher dose (6.8g) CLA had a significant increase in training time over the other groups. As it was a double blind test of obese and overweight individuals the fact that those who took the higher dose were not only able to work out more but also had a significant increase in LBM and decrease in BFM does seem like a positive correlation to me.

CLA is a scam. Just like 99.999% of the 'fat loss' products out there. Waste your money on it if you want.

Hey, thanks for you opinion. Without any research to back it up I would have to say you are talking out your butt, but that's par for the course here anyway right. I'm not saying it is some miracle drug, it is just a form of Fatty Acid after all. I don't take it personally (no problems with weight) but have researched it and know others who have had good results. So post up your findings...

It's funny how people differ-- when my stomach is empty I start crashing in a big hurry. I did a 30 mile run last year and ate quite a lot of food beforehand (breakfast of waffles, a banana, a Probar, and a big mug of coffee), as well as a couple of Gu packets, a Snickers bar, and then an entire meatloaf sandwich at mile 23.

"I get bad side stitches unless I run on a totally empty stomach" It's funny how people differ-- when my stomach is empty I start crashing in a big hurry. I did a 30 mile run last year and ate quite a lot of food beforehand (breakfast of waffles, a banana, a Probar, and a big mug of coffee), as well as a couple of Gu packets, a Snickers bar, and then an entire meatloaf sandwich at mile 23.

Good Grief!! I would have hurled! If I eat anything before about an hour in to the workout I feel horrible. I tried this last weekend just for kicks to see what would happen. I ate some grapes and an apple with my coffee. Then went for a run. At 30 minutes I started feeling so horrible I tried to self-rescue with a Carboom. One more 10 minutes later and a bunch of water and I could salvage my workout. Normally I can go 60 minutes on body sugar easily and then feed a little for the rest of the workout. Granted my post workout meals are pretty heroic... ;)

Hey, thanks for you opinion. Without any research to back it up I would have to say you are talking out your butt, but that's par for the course here anyway right. I'm not saying it is some miracle drug, it is just a form of Fatty Acid after all. I don't take it personally (no problems with weight) but have researched it and know others who have had good results. So post up your findings...

Um... I'm not a research scientists so I can't do any research on CLA. I can read some lame reports that other people post though, which isn't research. It's called reading crap... Did you even read the report that you linked? It's a bunch of crap. No control on diet or exercise. 'Study' performed on morbidly obese slobs. The very fact that you can find this product at GNC being pushed as a fat loss supplement says everything.